It passes Hohenwerfen Castle and reaches Bischofshofen in the Pongau district, then turns eastwards along the Salzburg Slate Alps to Eben and again southwards to Altenmarkt in the Enns Valley.

From here it reaches Rennweg in Carinthia through the 5.9 km (3.7 mi) long Katschberg Tunnel, leading downhill from the Hohe Tauern range to Spittal in the Drava Valley.

For centuries the 120 km (75 mi) long Hohe Tauern mountain range east of the Brenner Pass could only be crossed via steep and narrow mule tracks.

After the Austrian Anschluss to Nazi Germany, plans were drawn up by the Organisation Todt to build a motorway from Salzburg to the Carinthian capital Klagenfurt as part of the Reichsautobahn network.

Initial sections near the interchange with the later West Autobahn in the southern suburbs of Salzburg and a tunnel near Spittal an der Drau were already under construction when work ceased in 1942 because of World War II.

Construction was not resumed until 1968, upon a 1966 resolution of the Austrian National Council parliament, in view of the increasing mass tourism from Germany to the Adriatic Coast and the Gastarbeiter traffic to the Balkans and Turkey.

On 16 May 1975, within the section between Gmünd and Spittal, the falsework of a newly built bridge collapsed and fell from a height of 50 m (160 ft), killing ten workers.

[2] During the weekends in the summer months, extreme congestion occurred for the Tauern Tunnel, especially on Friday afternoons and Saturdays, with waiting times regularly increasing to 4 or 5 hours.